Greening the Parking Lot
Sustainability based landscape codes are the coming wave of landscape code technology. New landscape design standards are anchored in science so their effect upon the environment is definable and measurable. We see a tipping point in landscape governance documents with the introduction of sustainability-based landscape regulations. Landscape governance is moving toward sustainability in regard to landscape design.¹

The landscape code for the City of New Orleans is a pioneering sustainability-based landscape code.² This coastal city places emphasis on parking lot shading, paving, stormwater management, reducing urban heat, lowering energy consumption and increasing species diversity.

LEED and SITES
Two green building programs have been created over the last decade to allow for the design of green buildings and green building sites. These green building programs are known as LEED???EUR??? v4.1 and SITES???EUR??? v2.³ Both provide 'credits' that are evidence-based guidelines and performance benchmarks to produce and measure ecosystem services.

SITES and LEED practices are known to reduce energy usage, make building sites healthier and conserve or protect scarce natural resources. For site design, the SITES program is best suited. Parking lots in cities for instance need to be made greener and SITES credits allows this to happen.

Although several credits apply, the ones most central include SITES Credits 3.2, 3.4, 3.5, 4.9, 4.10, 4.12, 5.2, 5.3, 5.9, 6.4, 6.5, 6.6 and 6.9. There are other factors of course which apply to the design of green parking such as visual screening, beautification, spatial development and the use of color or texture. But these are principals that stem from traditional landscape design practice. SITES elevates parking lot greening to a more refined level.

Parking Lot Shading Criteria
The purpose of SITES Credit 4.12, (LEED SS Credit: Heat Island Reduction) for instance is to reduce the urban heat island effect. The UHI effect can be modified in three ways, add shade with trees or overhead shade structures, increase the reflectivity of pavement or convert up to 30% of the paved area as human or wildlife habitat landscape space.

 
Shade structures can be used to reduce temperature, transport stormwater and collect solar energy. And of course, shade structures in parking lots provide shade to automobiles and pedestrian walkways. Overhead architectural features can also be designed to reduce heat buildup from parking lot paving. Shade on parking surfaces may be created with overhead stretched fabric, wooden arbors, shade pergolas or even possible with the use of trellised overhead woody vines. Some communities are experimenting with overhead solar collectors within parking lots.

Lowering the temperature below sun screens reduce evaporative emissions of volatile organic compounds (VOCs) that emanate from cars stored in the sun. Interior temperatures within parked cars are reduced greatly as anyone who parks under a shady tree will attest. Shaded walkways within parking lots also can cool pavements but perhaps more importantly allow people to walk back and forth without exposure to harmful rays that cause skin cancers.

Replacing 30% of parking lot paving with natural areas that can be planted is a third method of reducing urban heat emanating from parking lots.
Rainfall is another valuable resource to be captured when overhead structures are used since planting beds for trees or shrubs are often adjacent to overhead structures. Many cities now require the capture of rain fall and channel it to nearby planting beds, bioswales, constructed wetland features or restored aquatic systems. ^{4, 5}

Sun Screens for Green Parking Lots
Perhaps the most effective way to shade pavements and to reduce the urban heat island problem is with the use of pre-engineered fabric shade structures. These, often called sun screens are very popular in the torrid south and southwest where parking lots can cook an egg sunny side up in a matter of seconds.

Parking lot shade structures have the capability of reducing air temperature up to 20 degrees while blocking up to 96% of the sun's ultraviolet strength. Car interiors parked under a shade structure can be 100?,?? cooler than those parked in an open lot. ⁶

Shade structures, such as those manufactured by Apollo Sunguard, are manufactured with engineered structural framing and custom cut specially treated UV tolerant fabric known as shade cloth. Shade structures can complement any building exterior trim and easily connect to walkways and landscape planting beds. Sun screens have a relatively long life span, but when replacement is needed, it is easy and quick to change out the fabric. Worn out fabric is recycled.

Modular shade structures are easy to work into the pattern of interior driveways, parking bays, planter islands and the interior walkway system. When properly sited in a North-South direction shade patterns move from sunrise to sunset covering on average between 80% and 40% of the parking surface.

Fabric structures can also be designed to cover walkways. A walk from a building to a parked car under a sun screen never exposes skin to solar radiation as well as providing moderate cover during rain storms or snow events. Shade structures in parking lots can be equipped with lighting systems, surveillance devices, solar panels and even electric charging stations. And of course, sun screens can be used at drop off and pick up zones as well as for bus parking bays within parking lots.

"Green parking lots" are those that provide ample shade, reduce heat, manage stormwater, lower energy use, provide effective screening and uses native plant material. Having a landscape code that greens parking one giant step toward building sustainability into the design of a city.

A designed green infrastructure system in which green parking plays an important role should be a goal all American cities. Cities and towns should adapt the SITES rating system into their local landscape governance documents, especially the community landscape code. ⁷

REFERENCES
1. Steiner, Frederick, Landscape governance: Prospects for the SITES Rating System, Socio-Ecological Practice Research (2020) 2:301-310. Springer Nature Singapore Pte Ltd. 2020.
2. City of New Orleans, Planning Commission, Comprehensive Zoning Ordinance, Article 23, Landscape & Screening 2020.
3. Sites v2, Sustainable Sites Initiative-Guidelines and Performance Benchmarks 2015, SITES v2, Green Business Certification Inc. 2014. LEED v4.1 United States Green Building Council, Green Business Certification, Inc, (USGBC). www.sustainablesites.org/report/.
4. Code City of Miami, Florida, Landscape Code, Article 9.8, Landscape Areas in Parking Lots, 2011.
5. Prince George's County Code, MC Corp, Subtitle 27, Zoning, Subdivision
6.-Landscaping, Buffering, and Screening, Sec. 27-563.-Authority Landscape Manual.
(See 2020 Revised Draft Landscape Manual)
6. Apollo Sunguard, Cooling Shade for Optimal Performance & Benefits, 2020.
7. Abbey, US Landscape Ordinances, John Wiley & Sons, 1998.


Note: Definition : Governance is the process (or documents) whereby elements in society wield power and authority, and influence and enact policies and decisions concerning public life, economic and social development." Landscape governance documents that do this are largely community landscape codes.

As seen in LASN magazine, January 2021.